Arcane focus 5e is a special item, varying the shape to different characters, maybe a crystal, a staff, a wand, a rod, or something similar, which can help a wizard, sorcerer, or a warlock to cast spells.
Arcane focuses can be used in place of minor material components, but not those which have a GP level associated with them.
Arcane Focus is a magical artifact that can help the caster make their spell more focused and solid. There are many different kinds of artifact which can help the caster cast magic spells, but for casting arcane spells, it is very important to possess an arcane focus 5e, whether it be in any form.
The purpose of a magic focus artefact is to replace the non-costly component of the spells, which can the spells weak. But if you do not have access to a focus or you do not own one, you cannot complete a spell without the non-costly materials.
The three main types of magical artefacts, a divine focus for divine magic casters and druidic focus, which helps the caster cast druids magic and the last one be Arcane focus 5e. All of these foci have a different and distinctive form than the other. You can choose whichever one you want to master and then further choose which type of foci is to your liking.
In normal circumstances, an arcane focus cannot be used as a weapon. It is an object that helps you cast powerful steps, but itself cannot be used as a weapon as it usually is in the form of a solid crystal, a wand, staff or rod, all weapons to cast spells but not used themselves. You can choose the arcane foci weapons in the starter’s table and polish and further develop it also. In the case where a focus is broken, the caster needs to give appropriate items as listed in the spell’s description and search for another focus.